Geopal Alarm Monitor for detector GJ-O2, GJ-OX and GP-O2is part of a new generation of gas alarm unit for detection of oxygen. The monitor type GJD L3C is used where only one detection point is needed, which requires just one detector. The present oxygen concentration is shown on a 2 line display on the monitor. The oxygen monitor is designed to receive and process the signal from the connected detector. It will carry out necessary follow-up signal processing and set off an oxygen warning and oxygen alarm.The relay circuits in the GJD L3C system has relay contacts for low alarm level, high alarm level and system error. The relay circuits facilitate the control of external functions like ventilation systems, magnet valves, alarm bells etc. The system can be calibrated so that the alarm is activated in the event of increasing or decreasing oxygen concentration. The central alarm unit is encased in a sturdy, granite-grey plastic cabinet with a transparent lid.